Digestion, Absorption, Excretion Small Piecesdstratto/bcor12/2009/32_Digestive.pdf ·...
Transcript of Digestion, Absorption, Excretion Small Piecesdstratto/bcor12/2009/32_Digestive.pdf ·...
1
Digestion, Absorption,
Excretion
Today’s topics:
• Digestive System
Hydrolysis
• Stomach, Liver,Pancreas
Absorption
• Intestine
• Excretion• Kidney (if time) 6 April 2009
Fig. 41-7
Ingestion Digestion Absorption Elimination
Undigestedmaterial
Chemical digestion
(enzymatic hydrolysis)Nutrientmoleculesenter bodycells
Smallmolecules
Mechanicaldigestion
Food
Piecesof food
1 2 3 4
Fig. 41-UN1
Bloodstream
Veins to heart
Lymphaticsystem
Small intestine
Esophagus
StomachLipids
Mouth
Hepatic portal vein
Absorbed food(except lipids)
Absorbedwater
Secretions from
the gastric glands
of the stomach
Secretions from the
pancreas and the liver
Liver
Rectum
Anus
Largeintestine
Fig. 41-8
Gastrovascularcavity
Food
Epidermis
Mouth
Tentacles
Gastrodermis
Cecum
Ascendingportion oflarge intestine
Gall-bladder
Smallintestine
Largeintestine
Smallintestine
Pancreas
Liver
Stomach
Appendix
Digestive System
Fig. 41-12b
Interior surfaceof stomach
Chief cells
Epithelium
Parietal cell
Pepsinogen and HClare secreted.
HCl convertspepsinogen to pepsin.
Pepsin activatesmore pepsinogen.
Chief cell
PepsinPepsinogen
HCl
H+
Cl–
Parietal cells
Mucus cells
Gastric gland2
3
1
1
2
3
2
Fig. 41-13
Oral cavity,pharynx,esophagus
Stomach
Lumen ofsmall intestine
Epithelium
of small
intestine
(brush
border)
Carbohydrate digestion
Polysaccharides
Smaller polysaccharides,maltose
Polysaccharides
Maltose and otherdisaccharides
Disaccharides
Protein digestion Nucleic acid digestion Fat digestion
Proteins
Small polypeptides
Pepsin
Pancreatic amylases
Salivary amylase
Disaccharidases
Monosaccharides
Small peptides
Amino acids
Amino acids
Polypeptides
Smallerpolypeptides
Pancreatic trypsin andchymotrypsin
Pancreatic carboxypeptidase
Dipeptidases, carboxypeptidase,and aminopeptidase
DNA, RNA
Pancreatic nucleases
Fat globules
NucleotidesFat droplets
Nucleosides
Nitrogenous bases,sugars, phosphates
Nucleotidases
Nucleosidasesandphosphatases
Glycerol, fattyacids, monoglycerides
Bile salts
Pancreatic lipase
(starch, glycogen) (sucrose, lactose)
Liver
Gallbladder
Pancreas
Spleen
Kidney
Stomach
Duodenum
Fig. 41-10a
Cecum
Ascendingportion oflarge intestine
Smallintestine
Intestine
Appendix
Intestinal villi and brush border
increase surface area for
absorption
http://www.vanderbilt.edu/exploration/text/index.php?action=view_section&id=1268&story_id=304&images=
Vein carrying bloodto hepatic portal vein
Villi
Intestinal wall
Key
Nutrientabsorption Capillaries
Villi
Lymphvessel
LactealEpithelial cells
Fig. 41-15
Absorption
Brush Border
Brush border
Key
Nutrientabsorption
Bloodcapillaries
Epithelialcells
Villi
Lymphvessel
Lacteal
Epithelial cells
Fig. 41-15b
Absorption
3
Back to the Liver
• Hepatic vein takes absorbed nutrientsto liver
– Adjust nutrient balance
– De-tox poisons
Liver is a majorprotein synthesis site
Maintaining
Glucose
Balance
Homeostasis:90 mg glucose/100 mL blood
Stimulus:Blood glucose
level risesafter eating.
Stimulus:Blood glucose
level dropsbelow set point.
Fig. 41-21
Cecum
Small intestine
HerbivoreCarnivore
Colon(largeintestine)
StomachSmall intestine
Colon
Fig. 41-19
Fig. 41-20
Esophagus
OmasumAbomasum
Intestine
Rumen Reticulum1 2
4 3
Liver
Gallbladder
Pancreas
Spleen
Kidney
Stomach
Duodenum
Kidney is a
blood filterCapillary
Excretion
Secretion
Reabsorption
Excretorytubule
Filtration
Filtra
teU
rine
Fig. 44-10
4
Fig. 44-14d
Loop ofHenle
Collectingduct
Bowman’scapsule
Glomerulus Kidney uses
osmosis to
concentrate
urine
Key
Activetransport
Passivetransport
INNERMEDULLA
OUTERMEDULLA
H2O
CORTEX
Filtrate
Loop ofHenle
H2O K+HCO3–
H+ NH3
Proximal tubule
NaCl Nutrients
Distal tubule
K+ H+
HCO3–
H2O
H2O
NaCl
NaCl
NaCl
NaCl
Urea
Collectingduct
NaCl
Fig. 44-15
Kidney uses
osmosis to
concentrate
urine
Key
Activetransport
Passivetransport
INNER
MEDULLA
OUTERMEDULLA
CORTEXH2O
300300
300
H2O
H2O
H2O
400
600
900
H2O
H2O
1,200
H2O
300
Osmolarity of
interstitialfluid
(mOsm/L)
400
600
900
1,200
100
NaCl
100
NaCl
NaCl
NaCl
NaCl
NaCl
NaCl
200
400
700
1,200
300
400
600
H2O
H2O
H2O
H2O
H2O
H2O
H2O
NaCl
NaCl
Urea
Urea
Urea